Can readTransaction and writeTransaction after a session.close()?

With my NestJs application, I want to create a Session by request and close it at the end of client request of my API. Unfortunately, I try this:

let session = this.neo4j.session();
session.close();
session.readTransaction(tx=>...);

And it works… I have my data. What is the mechanism behind all this? readTransaction and writeTransaction reopen the session? How can be sure to close really a session? Regards.

Neo4j Version: 3.5.3 Neo4j Mode: Single instance
Driver version: JS driver 1.7.6 Operating System: Linux Mint 19.2

Steps to reproduce

1. Create a session
2. Close it
3. Run a query with readTransaction or writeTransaction
4. Look the result

Expected behavior

Throw exception?

Actual behavior

I don’t know… I think readTransaction or writeTransaction reopen session.

[zhenlineo]

Hi @mehdikwa,

In 1.7, if you give a callback in session.close(callback), then once the callback is done, then all session resources (such as connections) are all released (return to a connection pool on driver).

The threads used on server is not strictly related to the connections the Neo4j server handles. Also the server has many thread pools besides the pool used by bolt server. If you want to change the default thread pool settings of bolt server, here are some instructions to change them.

[mehdikwa]

Hello,

If the session is still alive after closing it, will it mean that the session keeps an opened slot in the pool of connections and affects number of threads used in the cluster ? We are experiencing this behavior in a sense where we open a connexion for every function and closing it after return. But seems threads on server keeps increasing till overloading CPU usage.